Photographic multicolor diffusion transfer process using dye developers



Aug. 25, 1964 MULTICOLOR DIFFUSION TRANSFER PROCESS USING DYE DEVELOPERS Filed Aug. 22, 1960 I 1 s UPPORT 2o RECEPTION LAYER :u ALKALINE QUATERNARY AMMo/v/uM 22 sALT PROCESSING COMPOSITION rs I- HYDROQU/NONE DERIVATIVE LAYER w 2 1 52g: sLuE- SENSITIVE EMULSION LAYER 13 YELL WDYE DEVELOPER LAYER StaseI 18V j INTERLAYER -:.=,24. .:Z--jl 1=1:;-$ 24=.- GREEN-SENSITIVE EMULSION LAYER LIJIIHIHIIIIIIHIIHIHIII] /*MA6E"TA DYE DEVELOPER LAYER "/q\\ \\\\l INTERLAYER g5"- ""1: --RED- SENSITIVE EMULSION LAYER n I CYAN DYE DEVELOPER LAYER 10/ /////j/SUPPORT YELLow/MAE l 21 MAGENTA IMAGE Stage? Fig.2

213 C YAN IMAGE H YDROQU/NONE DERIVATIVE LAYER BLUE-SENSITIVE EMULSION, YELLOW DYE DEVELOPER LAYER EMULSION MAGENTA DYE 'DEvELofiER LAYER RED-SEAGITIVE EMULSION cYAN DYE DEvELPER LAYER SUPPORT WalierJW erls WilhoM.S nune' n uvmvrom mM mad/Z cream United States Patent 3,146,102 PHOTOGRAPHEC MULTTCQLOR DIFFUSIUN TRANSFER PROCESS USING DYE DE- VELOPERS Waiter J. Weyerts and Wiiho M. Salminen, Rochester,

N.-Y., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey v Filed Aug. 22, 196i), Ser. No. 50,963 '7 Claims. (Cl. 96-3) This invention relates to the art of photography and more particularly to a multicolor diffusion transfer process in photography and materials adapted to use in the process.

A diffusion transfer color process has been described in a number of patents, including British Patent 804,971, published November 26, 1958, wherein photographic elements containing silver halide emulsion layers and layers containing diffusible dye developers (dyes having a silver halide developing function) are exposed to record the latent image in the silver halide and then treated with an alkaline processing composition which permeates the emulsion layers and layers containing the dye developers which then develop the latent images to silver images. At the same time oxidation products of the dye developers are formed in situ with the silver images and which are relatively nondiifusing in the colloid vehicle of the layers. The non-diffusing character of the oxidized dye developers is apparently due at least in part to a decrease in solubility in the alkaline processing liquid, and may also be due to a hardening eifect of the oxidized developer upon the colloid vehicles of the layers which retards the diffusion of the oxidized dye developers. The residual unoxidized dye developers remaining in the layers in imagewise distribution are transferred by difiusion to a superposed reception element substantially to the exclusion of the silver image and oxidized dye developer to provide a positive dye image.

When an element containing differentially sensitized silver halide emulsion layers is used and subtractively colored dye developers are present in or contiguous to the respective emulsion layers, upon treatment with the processing liquid the dye developers are oxidized and rendered non-diffusing in the developed regions of the layers and the residual dye developer images in the positive regions are transferred by diffusion and in register to the reception element to provide a multicolor reproduction.

As is apparent, the success of the process depends in part upon the extent to which the dye developers in the exposed (negative) regions of the emulsion layers have been rendered substantially non-diffusing in the development reaction. Thus, if a quantity of unoxidized dye developer remains in a fully exposed negative region corresponding to the highlights of the subject, it will be transferred to the reception layer along with the unreacted dye developer in the positive regions and appears as high minimum density on the resultant color print. Typical dye developers such as 1,4-bis[fi-(2,5-dihydroxyphenyl)- ethyl amino] -anthraquinone are relatively weak silver halide developing agents even when used at the comparatively high pH of the order of 13 required in the process and do not so rapidly develop silver halide emulsion as to take full advantage of known sensitometric properties of the emulsions and to obtain dye images having a full scale of density and contrast expected with other developing agents. As a result, color prints obtained in the processes may exhibit an undesirable high minimum density in the highlight regions, low color saturation, contrast and density and the color separation is poor. These effects are due in part to the inefficiency of the dye developers as silver halide developing agents, the lack of discrimination of the dye developers for the silver halide they should develop and other factors.

Some improvement has been effected by employing an auxiliary colorless silver halide developing agent such as 1-phenyl-3-pyrazolidone in the processing composition to accelerate silver halide development and the immobilization of the dye developer in the sensitive elements. However, satisfactory multicolor prints are still not obtainable, particularly since the alkaline processing composition containing the auxiliary developing agents still does not cause the development to proceed so that the different dye developers of a multicolor system are each immobilized at the required rate, to the necessary extent and in the proper layer.

The above British patent, and other patents such as referred to hereinafter, relate to various features of the basic diffusion transfer color process using the dye developers, disclose how to carry out monochrome processes using the dye developers and that the monochrome principles of the particular invention are applicable to the multicolor reproduction. It has been discovered that when sensitive elements adapted to multicolor reproduction and containing a plurality of differently sensitized silver halide emulsion layers and contiguous dye developers for subtractive color reproduction are useful in the process, the problems of the multicolor process and solutions thereof, are much diiferent from those of the monochrome process. For example, the development products of one emulsion tend to effect the development of the other emulsions, the diffusion of a dye developer from a lower layer can be aitected, i.e., be hindered, by a dye developer or other substance in an upper layer, the exhaustion of the processing solution by an outer layer may affect development of a lower layer and one layer may not develop to the extent of another layer, and particularly one dye developer may not be immobilized sufficiently to prevent it from transferring and causing color contamination of a dye image of another color. Also, a given dye developer may develop some grains of silver halide in the wrong emulsion layer with the result that an insufficient amount of that dye developer is available for transfer and the corresponding colors are unsaturated, thus a magenta dye developer may develop some grains of red sensitive silver halide and become immobilized thus decreasing the magenta available to produce red colors which then appear unsaturated. The present invention embodies sensitive multilayer elements and procedures which tend to overcome or compensate for such interaction or interdependence of the various layers, dye developers and other ingredients of a multilayer system, with the result that multicolor reproductions are obtained having a quality higher than previously believed to be possible.

According to the present invention the multicolor transfer processes using dye developers are carried out in contiguity with certain substantially colorless onium compounds diifusible in alkaline solution through the organic colloid layers of the sensitive elements. The onium compounds of the invention are heterocyclic quaternary am- Patented Aug. 25, 1964 monium compounds capable of forming methylene bases soluble in alkaline solution and which quaternary ammonium compounds are diffusible in alkaline solution through organic layers of the sensitive elements. The compounds may be present in the alkaline processing composition, in the reception element or in the lightsensitive element containing the dye developers. The advantageous effects of the quaternary ammonium compounds becorne especially evident when the process is carried out in the presence of both the quaternary ammonium compounds and certain substantially colorless auxiliary silver halide developing agents including certain hydroquinone derivatives, these developing agents preferably being present in the light-sensitive element, and the quaternary ammonium compounds preferably being present in the alkaline processing fluid or in the reception element or in both. A preferred embodiment of the invention includes the use of pyridinium compounds which form diffusible methylene bases in alkaline solution, in combination with hydroquinone derivatives which are substantially colorless, substantially water-insoluble, and soluble and ditfusible in alkaline solution through the organic colloid layers of the sensitive element.

As a result the mentioned contamination of colors is reduced and the saturation of colors is improved as well as other characteristics of the process. That is, quaternary ammonium compounds, and indeed onium compounds, in general, are effective in improving the color quality of the prints in some, but not necessarily the same, respects. However, we have found that the heterocyclic quaternary ammonium compounds of the invention which form the methylene bases in alkaline solution, are distinct in their behavior from other quaternary ammonium compounds which do not form methylene bases. For example, the quaternary ammonium compounds, as a class, reduce color contamination of the dye developer prints, however, the heterocyclic quaternary ammonium compounds of the invention not only reduce color contamination, but also greatly reduce color dropoff and other undesirable characteristics of the process such as minimum density. Color contamination usually appears in the prints as a degradation of one or more colors by one or more other colors and may be due to the failure of one or more dye developers to be immobilized sufficiently to prevent them from transferring from regions where they should have been immobilized. Drop-off appears as a degradation in color quality of the prints apparently caused by one dye developer developing silver halide grains in the wrong emulsion layer, e.g. the magenta dye developer developing some red sensitive silver halide grains with the result that more magenta dye developer is immobilized than should be and the red colors are thus deficient in magenta. The mentioned effects of the heterocyclic quaternary ammonium compounds forming the methylene bases, when used alone or in combination with the hydroquinone derivatives, is particularly evident when the organic colloid vehicle of the sensitive element containing the dye developers, is composed principally of gelatin. Many of the common optical sensitizing dyes are quaternary ammonium salts but they are ordinarily not useful in place of the colorless quaternary ammonium compounds particularly because they are not sufficiently soluble and diffusible and they impart stain to the prints.

One object of the invention is to provide photographic elements comprising several superposed differentially sensitized silver halide emulsion layers having contiguous dye developers and preferably also the contiguous hydroquinone derivatives, and to provide means for processing the elements in contiguity with the heterocyclic quaternary compounds. Sensitive elements, processing compositions and reception elements particularly adapted to the taking of pictures in a camera and the processing thereof in a camera will be provided.

The objects of the invention are accomplished in part by description hereinafter of representative sensitive elements comprising a plurality of silver halide emulsion layers differentially light-sensitive (sensitive to different regions of the spectrum), having contiguous dye developers which may be subtractively colored with respect to the sensitivity of the corresponding emulsion layer and preferably contiguous hydroquinone derivatives, and by processing the exposed element by wetting with alkaline processing solution in contact with the reception layer in contiguity with the quaternary ammonium compounds, to develop the exposed silver halide in the emulsion layers and thereby render the dye developers thereof non-diffusing in the regions of development, and allowing the dye developers in the undeveloped regions to transfer imagewise by diffusion and in register to the reception layer to yield a multicolor dye developer image thereon.

In the accompanying drawings are shown in greatly enlarged cross-sectional view the appearance of representative elements employed in a typical process of the invention.

In FIG. 1 of the drawings is shown in flow-sheet form a typical process embodying our invention according to which in Stage 1 the sensitive element comprises a support 10, layers 11, 12 and 13 containing subtractively colored alkali-soluble cyan, magenta and yellow dye developers, the light-sensitive halide emulsion layers 14, 15 and 16 sensitive to red, green and blue light respectively, the interlayers 17 and 18 separating the green-sensitive emulsion and its contiguous subtractively colored magenta dye developer layer from the other layers and the overcoating layer 19 containing a developing agent such as one of the hydroquinone compounds of the invention. The reception element containing support 20 and reception layer 21 (which may contain the pyridinium salt) is positioned so as to receive dye images transferring by diffusion from the sensitive element, with a rupturable container of alkaline, pyridinium salt processing solution 22 therebetween. Upon rupture of the container 22 as by means of passing the assembly between rollers in a camera so as to distribute the contents uniformly across a predetermined area of the sensitive element, the solution penetrates layer 19 dissolving the substantially water-insoluble, alkali-soluble and diffusible hydroquinone derivative and transporting it to the under lying layers Where the latent images in the silver halide of areas 23, 24 and 25 are developed to silver and the dye developers in the areas contiguous to areas 23, 24 and 25 each become immobilized and rendered non-diffusing. Thereafter, the unreacted dye developers of layers 11, 12 and 13 diffuse imagewise in register to the reception layer 21 and form the dye images thereon. The method of preparation of the described sensitive element and its use in the processes of the invention is described here-- inafter.

In FIG. 2 of the drawings is shown an element in which the dye developers are incorporated into the differentially sensitized emulsion layers 31, 32 and 33, and the hydroquinone derivative is present in the layer 34 outermost from the support.

In FIG. 3 of the drawings is shown in schematic form, a light-impervious enclosure useful for processing an exposed roll of film containing silver halide emulsions and dye developers so as to wet the film with alkaline activator solution and bring it into contact with a mordanted reception sheet for transfer of several multicolor dye developer images to the sheet.

It is believed that the quaternary compounds interact with the dye developers to form salts thereof and that the improvements particularly in density and highlights are at least due in part to the effect of such salt formation on the solubility and diffusibility of the dye developers. There is evidence that the quaternary compounds actually temporarily delay the migration of the dye developers so that the initial diffusion rates of the dye developers are reduced, yet more of the dye developers transfer from less exposed areas to increase the density.

Onium compounds have'been used in the photographic art for quite some time. For example, U.S. Patent No. 2,648,604 discloses the use of non-surface-active quaternary ammonium compounds as development accelerators and U.S. Patents Nos. 2,271,623, 2,271,622 and 2,275,727 disclose the use of quaternary ammonium, quaternary phosphonium and tertiary sulfonium compounds as sensitizers for silver halide emulsions. Notwithstanding the fact that such onium compounds have been previously used as sensitizers and as development accelerators, the mentioned results obtained by using the quaternary compounds in conjunction with the dye developers in the diffusion-transfer process of this invention are worthy of note. In the process disclosed in the above-mentioned U.S. patents, there is an increase in silver density in the negative due to the use of the onium compounds; however, the increase in density in such processes takes place in the exposed areas of the negative and is attributable to the above-mentioned ability of the onium compounds to sensitize an emulsion or to accelerate development. In the present processes, the increase in density which takes place in the positive image is primarily the result of increased transfer of the dye developer from unexposed areas of the negative. The fact that the quaternary compounds would coact with dye developers to increase the transfer of such dye developers from unexposed areas of the negative in no Way was expected from the prior use made of such compounds as sensitizers or development accelerators. Furthermore, the improvements in the present processes are not necessarily the result of improved surface activity due to the onium compounds because the onium compounds which usually bring about the greatest improvement in density would not be generally classified as surface active. It is believed that the increase in density is at least due in part to the ability of the onium compounds to increase the solubility of the dye developers.

. The fact that the onium compounds would also act, especially in the presence of the hydroquinone derivatives, to inhibit transfer of the oxidized dye developers from the exposed areas and thus improve the highlights, was similarly unexpected. This improvement in highlights is believed to be due to the ability of the onium compounds to control, especially in the exposed areas, the diifusibility of such dye developers.

It will be seen from our co-filed U.S. patent application Serial No. 50,962, that onium compounds, including ternary sulfonium, quaternary phosphonium and quaternary ammonium compounds, are in general effective in improving the color quality of the dye developer prints in some, but not necessarily the same, respects. The present quaternary compounds which form the methylene bases are distinct in their activity from the other onium, and even other quaternary ammonium compounds.

That is, the onium compounds all appear to at least reduce the mentioned color contamination whereas the present quaternary compounds not only reduce color contamination but also reduces drop-01f and have other beneficial effects. These differences are especially noticeable when auxiliary developing agents such as the colorless hydroquinone derivatives (below) are present.

The particularly efiicacious heterocyclic quaternary ammonium compounds which form the methylene bases diifusible in alkaline solution have the general formula 1 RI TZ OHCH)n OOH R' wherein D represents the non-metallic atoms necessary to complete the heterocyclic nucleus of the quaternary ammonium compound containing 1 or more of the reactive methyl groups -CH R' in one or more of the nuclear positions, the other nuclear positions being substituted or not, such as quaternary salts of the pyridine, quinoline, benzoquinoline, benzoxazole, benzoselenazole, thiazole, benzothiazole, naphthothiazole, benzimidazole, isoquinoline series, etc., n is 0 or 1, R is an alkyl group, an aryl or aralkyl group of the benzene series, or substituted alkyl, aryl or aralkyl groups of the benzene series, the alkyl chains preferably being lower alkyl of from 1 to 4 carbon atoms, R is a hydrogen atom or one of the groups represented by R, and X represents OH or an acid anion such as Br, CH SO; or

One or more of these compounds can be used alone or in combination with the other onium compounds which do not form the methylene bases and are advantageously employed in either the processing solution, the reception element, or both, and less desirably in the light-sensitive element per se, to improve the print quality by a mechanism not fully understood. When the hydroquinone derivatives are also present a co-action with the quaternary compound takes place such that a greatly improved effect is obtained distinguishable from the effect of either the hydroquinone derivative or the quaternary compound. The dye prints obtained exhibit appreciably less color contamination and improved color saturation, density and contrast.

The quaternary compounds can be used in varying amounts depending upon the particular compound. When used in the alkaline processing fluid, useful results are obtained which form about 0.2 to 15% of the compound. In some cases about 0.2 to 3% is best. Similarly, the amount used in the sensitive element and receiving sheet will vary with the compound selected.

The quaternary ammonium compounds comprising a preferred embodiment of the invention are pyridinium salts which form the diffusible methylene bases and which have the above formula, the pyridinium nucleus being substituted with from 1 to 3 active methyl groups -CH R' present in at least one of the 2, 4 or 6 positions, e.g., a lower alkyl group such as methyl, ethyl, propyl or substituted lower alkyl groups such as hydroxyalkyl, e.g., hydroxyethyl, which alkyl groups act as methylene base precursors. Positions 3 and 5 may or may not be substituted with e.g. halogen, lower alkyl and haloalkyl groups such as chlorine, methyl, ethyl, propyl or chloroethyl groups.

Typical salts have the above formula as are follows: 1-benzyl-2-picolinium bromide CH i a eN pts i CH L g 3 (5411350? I ot-Picoline-fl-naphthoylmethylbromide CH Br- 1-,B-phenylcarbamoyloxyethyl-2-picolinium bromide i CH3 BI (i 2H4OCONHC/6H5 1-methyl-2-picolinium pts l-phenethyl-2,4,6-trimethylpyridinium bromide 1-phenethyl-4-n-propylpyridinium bromide 4-y-hydroxypropyl-l-phenethylpyridinium bromide and l-n-heptyl-Z-picolinium bromide A number of pyridinium salts having the above general formula do not form methylene bases sufiiciently diffusible in alkaline solution to be of practical use in the process, e.g., l-n-decyl-Z-picolinium bromide 1,2-dibenzyl pyridinium bromide 6-amino-l-phenethyl-Z-picolinium bromide Z-amino-l-phenethyl-4-picolinium bromide Z-benzyl-l-phenethyl pyridinium bromide 4-benzyl-1-phenethyl pyridinium bromide The following which do not form methylene bases in alkali solutions are also less useful. l-phenethyl pyridinium bromide l-ethyl pyridinium bromide 1-phenethyl-3-picolinium bromide l-n-nonylpyridinium pts A number of silver halide developing agents can be used in the process, as auxiliary developing agents, in

conjunction with the quaternary compounds forming the Phenylhydroquinone 2'-hydroxyphenylhydroquinone Phenoxyhydroquinone 4-methylphenylhydroquinone 1,4-dihydroxynaphthalene 2- (4-aminophenethyl --bromohydroquinone 2-(4-aminophenethyl)-5-methylhydroquinone 4'-aminophenethylhydroquinone 2,5 -dimethoxyhydroquinone 2,5-dibutoxyhydroquinone m-Xylohydroquinone Bromohydroquinone 3 ,6-dichlorohydroquinone 2-dimethylaminomethyltoluhydroquinone 2-cyclohexylhydroquinone Sec. butylhydroquinone 2,5-dichlorohydroquinone 2,S-diisopropylhydroquinone 2,5-diiodohydroquinone 3-chlorotoluhydroquinone Tetrachlorohydroquinone 2,5 -diphenylhydroquinone 2,S-diresorcylhydroquinone 2,5-dioctylhydroquinone Dodecylhydroquinone The useful hydroquinone derivatives are particularly distinguished from the dye developers containing hydroquinonyl moieties mentioned hereinafter, in being substantially colorless and therefore do not impart any color to the print.

The processes of the invention are thus carried out with the silver halide emulsions and dye developers in contiguity with the quaternary ammonium compounds, and if desired also the hydroquinone derivatives. That is, the quaternary compounds may be present in either or both the alkaline processing fluid and the reception sheet, less desirably in the sensitive element, and the hydroquinone derivative preferably in any of the layers of sensitive element such as an overcoating layer, emulsion layer, dye developer layer, an interlayer or in the reception sheet. As mentioned, for some purposes the hydroquinone derivatives and other developing agents may be present in the processing fluid; however, in the present invention use in the fluid is less desirable since the hydroquinone derivatives are unstable in such solutions and readily undergo oxidation accompanied by discoloration of the prints.

The hydroquinone derivatives are preferably incorporated into emulsion layers, overcoating, interlayers or other layers, as dispersions in the hydrophilic organic colloid vehicle of the layer. The hydroquinone derivatives may be dissolved in alkaline solution and precipitated into aqueous gelatin solutions by raising the acidity of the solution. However, this is a less desirable procedure because of the instability of the compounds in alkaline solution. The hydroquinone derivatives may be dissolved in a solvent, such as a lower alcohol, and precipitated into aqueous gelatin solutions for coating on the sensitive element. They may be added to gelatin solutions which are ball-milled to reduce the crystal size. However, the hydroquinones are preferably dissolved in a low molecular weight water-insoluble organic crystalloidal solvent permeable to the alkaline processing solutions and having a boiling point above about 175 C. such as dibutyl phthalate and added to an aqueous gelatin solution which is passed through a colloid mill until the desired degree of subdivision has been attained. An auxiliary organic solvent can also be used such as one having a solubility in water greater than that of the crystalloidal solvent, of the order of at least about 2 parts per parts of water. Thus the auxiliary organic solvent can be washed from a chilled gelatin dispersion in the presence of the other solvent. The auxiliary solvent may be one having a boiling point at least about 25 C. lower than the crystalloidal solvent in order that it can be removed by volatilazation during the drying of a coating to leave the hydroquinone derivative dispersed in only the crystalloidal solvent. As a result, the hydroquinone derivatives are quickly and uniformly dissolved by the alkaline processing composition and transported throughout the sensitive element to produce more uniform development than when the hydroquinone derivatives are incorporated into the element by other means.

The hydroquinone derivatives may be used in one or more layers of the sensitive element in quantities of the order of from about 10 to 100 mgs. or more per square foot. However, the quantity used depends in part upon the amount of silver halide, the layer in which it is contained, the amount of dye developer and the amount of pyridinium salt in the sensitive element or processing solution of reception element. In some instances it may be desirable to form a complex of the hydroquinone derivatives by reaction with sulfur dioxide in a well-known manner and to incorporate the complex in the overcoating layer, outer emulsion or other layer of the sensitive element. These hydroquinone-sulfur dioxide complexes tend to be more stable than the hydroquinone derivatives themselves.

The dye developers which are used in the emulsion layers or in layers adjacent to the emulsion layers are compounds which are both a silver halide developing agent and a dye. They are characterized by being relatively non-difiusible in the colloid layers at a neutral pH but diffusible in the layers in the presence of the alkaline processing solutions. For the most part the dye developers are insoluble in water per se, which property usually necessitates the use of organic solvents to incorporate the dye developers into the organic colloid layers of the sensitive elements. Otherwise, the solubility of the dye developers is not particularly important and so long as the dye developers are capable of being immobilized in the layers in the presence of the alkaline processing solution and they are transferrable to the reception element, they are useful in the process of the invention. The dye developers are particularly characterized by containing both a chromophore moiety and at least one moiety such as a hydroquinonyl radical having a silver halide developing agent function and which radical imparts silver halide development activity to the dye developer molecule as a whole with the result that during development of a silver halide image, the dye developers are oxidized to less difiusible compounds in the region of exposure and development and the residual dye developers in the undeveloped regions are transported imagewise to mordanted reception layers to provide a dye image thereon. The dye developers of course should not have a desensitizing action toward silver halide emulsions.

Representative dye developers of use in the sensitive elements of the invention have the general formula in which M is an aromatic or heterocyclic ring or ring system such as a benzene, naphthalene, tetralin, anthracene, anthraquinone, pyrazole, quinoline, etc., ring and may also be substituted, as by hydroxyl amino, keto, nitro, alkoxy, aryloxy, acyl, alkylamido, arylamido, alkyl, aryl, carboxamido, sulfonamido, carboxyl or sulfo groups. D represents a silver halide developing agent moiety imparting the developing agent function to the dye developer such as a hydroquinolyl group which may be substituted with amino, alkylamino, alkyl, hydroxyl, alkoxyl or halogen groups.

A very useful type of dye developers disclosed in Australian Patent 220,279, accepted December 17, 1958, and German Patent 1,036,640, August 14, 1958, have the general formula Y-RArN=N Q l and YArN=N Q I: )m P wherein P=1 or 2; R=an alkylene group of from 1 to 5 carbon atoms; Ar=an aryl group of the benzene or naphthalene series; each Z=a lower alkyl group such as methyl or ethyl, or halogen e.g. chlorine; Z=a lower alkoxyl group such as methoxy or ethoxy, halogen or lower alkyl group; m=0, 1 or 2; Y=a 2,5- or 2,3- or 3,4-

dihydroxyphenyl group which may be substituted by alkyl or halogen groups; Q=the residue of a coupling component such as a phenol, naphthol, S-pyrazolone or open chain reaction methylene coupler containing the group COCH -CO, for example:

4-[p-(2,5 dihydroxyphenyl)-phenylazo]-5-acetamido-1- naphthol.

V 4 [p (2,5' dihydroxyphenethyl)-phenylazo]-5-benzamido-l-naphthol.

l phenyl 3 methyl-4-[p-(2,5'-dihydroxyphenethyl)- phenylazo] -5-pyrazolone.

2 [p (2',5 dihydroxyphenethyl)-phenylazo]-4-acetamide-l-naphthol.

2 [p-(2,5-dihydroxyphenethyl)-phenylazo]-4-amino-1- naphthol.

OH (])H 2C 2 N=N (magenta dye developer) 1 l O H O 0 H 2- [p- 2',5 -dihydroxyphenethyl) phenylazo] -4-methoxyl-naphthol.

2-[p-(2,5'-dihydroxyphenethyl) phenylazo]-4-ethoxy-1- naphthol.

2-[p-(2',5' dihydroxyphenethyl) phenylazo]-4-n-propoxy-l-naphthol (Compound II).

1-phenyl-3-N-n-butyl-carboxamido-4- [p- (2',5 '-dihydroxyphenethyl) -phenylazo] -5-pyrazolone.

1-phenyl-3 -N-n-hexylcarboxamido-4- [p- (2',5 -dihydroxyphenethyl) -phenylazo] -5-pyrazolone (Compound III) 1-phenyl-3-carbethoxy-4- [p- 2,5 -dihydroxyphenethyl phenylazo] -5-pyrazolone.

2- [p- 2,5 -dihydroxyphenethyl) -phenylazo -4- isopropoxyl-naphthol 1-phenyl-3-N-cyclohexylcarboxamido-4- [p- 2',5 '-dihydroxyphenethyl -phenylazo] -5-pyrazolone.

1-phenyl-3-phenyl-4- [p- (2,5 -dihydroxyphenethyl) phenylazo] -5-pyrazolone.

2- (4- [p- 2",5 "-dihydroxyphenethyl) -phenylazo] -ocnaphthylazo -4-methoxyl-n aphthol.

1-phenyl-3-amino-4- (4- [p- (2",5"-dihydroxyphenethyl phenylazo] -2',5-diethoxyphenylazo -5-pyrazolone.

l-acetoxy-2- p- (,B-hydroquinonylethyl -phenylaz0] 4-methoxy naphthalene.

4-isobutoxy-2- [p- (,8-hydroquinonylethyl) -phenylazo] l-naphthol.

1-acetoxy-2- p- (fi-hydroquinonylethyl) -phenylazo] 4-propoxy naphthalene.

2- [p- 2,5-dihydroxy-4'-methylphenethyl) phenylazo] 4-propoxy-1-naphthol.

1-phenyl-3- [N- fl-ethylhexyl) -carboxamido] -4- [p- (B'- hydroquinonylethyl -phenylazo] -5-pyr azolone.

1-phenyl-3- (N-n-heptyl) carboxamido-4- [p- (fi-hydroquinonylethyl) -phenylazo] -5-pyrazolone.

1- o-carboxyphenyl) -3-phenyl-4- [p- 2,5 -trifluoro acetoxyfl-phenylethyl phenylazo] -5-hydroxy pyrazole lactone.

1- o-carboxyphenyl) -3-N-phenylcarboxamido-4- [p- 3'- hydroquinonylethyl) -phenylazo] -5-hydroxypyr azole lactone.

1 1 Another class of dye developers disclosed by British Patent 804,971, November 26, 1958, and British Patent 804,973, November 26, 195 8, have the general formula wherein A represents an anthraquinone nucleus, D represents an organic radical having a developing function and containing an aryl nucleus such as benzene or naph thalene nuclei, substituted by at least two substituents selected from hydroxyl, amino and substituted amino groups so that the resulting compound is capable of developing exposed silver halide, Q represents a hydrogen atom or an alkyl group or, when the substituents on the aryl nucleus of D are hydroxyl groups, Q may also be an acyl group, which may be aliphatic, e.g., acetyl or aromatic, e.g. benzoyl, Z is a bivalent organic radical containing at least one methylene (CH group, In is a positive integer less than 5 and each Y may be a hydrogen or halogen atom or an amino, alkyl, aryl, nitro, alkylamino, arylamino, aryloxy, alkoxy, hydroxyl, sulphonamido, carboxamido, carboxy, sulpho,

Q t 1q D or N Z D group.

Examples of these dye developers are:

1,4-bis- 2',5 -dihydroxyanilino -'1nthraquinone,

1,5 -bis 2,5 -dihydroxyanilino -4,8-dihydroxyanthraquinone,

1,4-bis [fl- 3 ',4-d ihydroxyphenyl -ethylamino] anthraquinone,

(cyan dye developer) In Formula 1 above the expression bivalent organic radical Z refers to organic radicals having the two free valences attached to different atoms. As examples of 12 such suitable bivalent organic radicals, mention may be made of alkylene radicals such as --CH CH --CH (3H3 CH2(I]H as well as bivalent radicals such as It is also intended that Z may be saturated, unsaturated, such as -CH CH:CHCH

or substituted, such as chloroalkylene or hydroxyalkylene. Where Z is an alkylene group, best results are obtained by the use of a lower alkylene group, e.g. an alkylene group, containing less than about six carbons, and preferably an ethylene (-CH CH group. Alkylene groups containing more carbon atoms may be used, however, providing that the resulting dye developer is capable of being dissolved in the liquid processing composition described herein, and its oxidation product rendered immobile in the developed emulsion layer.

Acylation of amino-nitrogen atoms which are part of the chromophoric system has the effect of shifting the Visible absorption band of the compound toward higher frequencies (shorter wavelengths). Thus, acylating one amino-nitrogen of the cyan, 1,4-bis-[fi-(2,5-dihydroxyphenyD-ethylamino]anthraquinone changes its color to a magenta, and acylating both the amino-nitrogen atoms changes its color to an orange-yellow. Similarly the acylation of hydroxyl groups of the above types of dye developers can be expected to shift the color of the dye developers. Thus, the dye developers may undergo a change in structure and/or color during the development reaction, for example through hydrolysis, and the dye which is transferred may have a color different than that of the dye developer originally present in the sensitive element.

Additional dye developers are disclosed in Belgium Patent 554,935, British Patents 804,971, 804,9735 and French Patent No. 1,168,292.

The following dye developers are also useful in the sensitive elements and processes of the invention:

Cyanurated dye developers such as 2-hydroquinoneamino-4- (p-phenylazo) anilino-6-hydroXy-4-triazine (Canadian Patent No. 579,038).

Anthraquinone dye developers such as 1,4-bis-(2',5'- dihydroxyanilino -anthraquinone and 1,4-diamino-N-(fl- 2',5' dihydroxyphenyl-or-methyl-ethyl)-2,3-anthraquinone-dicarboximide.

Amino substituted anthraquinone dye developers such as prepared by reaction of 1-amino-4-(p-aminoanilino)- anthraquinone-Z-sodium sulfonate with chloroacetamido hydroquinone monobenzoate.

Dye developers obtained by reaction of 1-phenyl-3- amino-4-phenylazo-5-pyrazolone or 1,4-bis-(B-aminoethylamino)-anthraquinone with homogentisic acid lactone or acid chloride, or gentisic acid chloride e.g. 1-phenyl-3- (2,5 dihydroxyphenyl-acetamido)-4-phenylazo-5-pyrazolone (Blout et al. Canadian Patent 577,021, dated June 2, 1959).

Naphthamide dye developer such as 1-(2,5-dimethoxyphenylazo) 2 hydroxy N-(2,5'-dihydroxyphenyl)-3- naphthamide (French Patent 1,168,292, dated August 25, 1958).

Disazo dye developers such as 2-[p-(1-hydroXy-3,6- disulfo 8-amino-2-naphthylazo)-3,3-dimethoxybisphenyleneazoJ-hydroquinone and 2-(2,5-dimethoxy-4'-[p- (2",5" dihydroxyphenethyl)phenylazo]-phenylazo)-1,8- naphthalene dio1-3,6-disulfonic acid.

Arylazonaphthol dye developers, e.g. 1-amino-4-phenylazo-Z-naphthol.

Anthrapyridone dye developers e.g. 1-acetyl-3-fi-(2,5'- dihydroxyphenyl) ethyl 6-p-(2',5'-dihydroxyphenyl)- ethylaminoanthrapyridone.

Thiohydroquinone dye developers, e.g. 1 phenyl 3 methyl 4 [p-(2',5'-dihydroxyphenylthioethyl)-phenylazo]--pyrazolone (Belgium Patent 568,344).

Ortho coupled dye developers exhibiting limited sensitivity to changes of pH e.g. 2-(p-[2",5"-dihydroxyphenoxy]phenylazo)-4-methoxy-l-naphthol and l-phenyl-3- methyl 4-[p-hydroquinolylsulfonyl)-pheny1azo]-5-pyrazolone.

Oxalyl ester dye developers, e.g. 1-phenyl-3-amino-4- [p (2,5' bis-ethoxalyloxyphenethyl)-phenylazo]-5- pyrazolone.

Leuco compounds may be used similarly e.g. l-phenyl- 3 methyl 4-(2'-methyl-4'-diethylamino)anilino-i-pyrazolone, which do not exert a filtering action on underlying emulsion layers and which are immobilized in the developed regions, diifuse imagewise from undeveloped areas to the reception layer and are oxidized to colored images therein.

The dye developers may be incorporated into the emulsion layers or into the layers thereunder by several methods. For example, the dye developers may be dissolved in organic solvents and precipitated into gelatin solution or the dye developers may be ball-milled in gelatin solutions to reduce their particle size. However, particularly favorable results are obtained when the hydroquinone derivatives of the invention are present in one or more of the layers of the sensitive element and the dye developers have been incorporated into the gelatin layers under the emulsion layers (as shown in FIG. 1) by dissolving the dye developers in high boiling solvents such as ditetrahydrofurfuryl adipate or 2-(2-butoxyethoxy)ethyl acetate and milling the mixture in gelatin solution in a colloid mill. When high boiling solvents having low solvent activity for the dye developers, such as dibutyl phthalate, are used it is desirable to dissolve the dye developer in a mixture of the high boiling solvent and a low boiling solvent such as cyclohexanone, methanol, etc., which evaporates readily from the coatings during the subsequent drying operation. Many of the dye developers can be used with the high boiling solvents (in absence of low boiling solvents) such as the followmg:

Ditetrahydrofurfuryl phthalate fi-Methoxyethyl phthalate Ethyl N,N-di-n-butylcarbamate Guaiacol acetate (o-methoxyphenyl acetate) Tetrahydrofurfuryl propionate Triethyl citrate Acetyl triethyl citrate T ricresyl phosphate Tri-p-tert. butylphenyl phosphate Triethylphosphate Tri-n-butylphosphate Triphenylphosphate Isoamyl acetate Ditetrahydrofurfuryl succinate Methyl acetate Ditetrahydrofurfuryl adipate Tetrahydrofurfuryl benzoate N-n-amylphthalimide Ethyl N,N-di-n-butylcarbamate Diethyl lauramide Dibutyl lauramide Lauroyl piperidine N-n-butyl acetanilide Tetraethyl phthalarnide N-n-amyl succinimide 4-methyl-2-pentanol 2,4-di-n-amylphenol Ethylene glycol monobenzyl ether Methyl isobutyl carbinol Furfuryl alcohol Cyclohexanone 2-(2-butoxyethoxy)ethyl acetate The isomeric 2-, 3- and 4-methylcyclohexanones are particularly useful lower-boiling solvents for use with the above high-boiling solvents for dispersion of dye developers such as the cyan dye developers l,4-bis-(2,5-dihydroxyphenylisopropylamino) anthraquinone, 5,8- bis[fl hydroquinoyl a-methyl)ethylamino]quinizarin and 1,4 bis (2,5-dihydroxyphenylisopropylamino)-5- hydroxyanthraquinone, and the magenta dye developer 4 methoxy 2-[p-(B-hydroquinoylethyl)-phenylazo]-lnaphthol. As a result the gelatin solutions containing dispersions of dye developers produce stable dried coat: ings in which the dye developers do not tend to crystallize out.

The dye developers are employed in the sensitive ele ments contiguous to the silver halide of the emulsion layers, that is, they may be present in one or more of the emulsion layers or preferably in a hydrophilic organic colloid layer immediately next to and particularly under the silver halide emulsion layer. Especially good results are obtained when the dye developers are positioned so as to be present in the layer immediately under the emulsion layer, the sensitivity of which is complementary to the color of the dye developer as shown in FIG. 1 of the drawings. It appears less desirable to locate the dye developer in a layer positioned above the corresponding layer of silver halide emulsion. The contiguity of the dye developer with respect to the silver halide can take the form of a mixed packet system wherein the dye developer may be present in a matrix surrounding a particle or globule containing silver halide grains.

In multilayer sensitive elements of the type shown in FIG. 1 the order of arrangement of the diiferentially sensitized silver halide emulsion layers on the support can be different, e.g. reversed so as to have the blue-sensitive emulsion layer on the support and the red-sensitive emulsion layer outermost. In such arrangements of layers the sensitivities of the silver halide emulsions should be adjusted so as to prevent recording unwanted blue light images in the emulsions primarily sensitive to the red and green regions of the spectrum e.g. a silver bromide emulsion can be used for the blue sensitive emulsion and silver chloride emulsions for the other layers. In instances of this type it may be desirable to utilize the leuco compounds mentioned above in place of one or more of the dye-developers which, since they may have some blue absorption, might tend to exert an undue filtering action on the blue-sensitive bottom emulsion layers.

The hydrophilic organic colloid vehicle of the emulsion layers, overcoating layers, of the dye developer layers and of interlayers can be varied somewhat, for example, gelatin, gelatin derivatives such as dibasic acid esters of gelatin, polyvinyl alcohol and cellulose acetate hydrogen phthalate, or mixtures of these may be used. However, the best and most consistent results, and consequently prints of highest quality, are obtained when gelatin is used as a colloid vehicle throughout all layers of the sensitive element. In fact, when gelatin interlayers are used as shown in FIG. 1 of the drawings, they should be at least 75% of the measured thickness of the yellow dye developer layer and contain at least about two times the amount of gelatin present in that layer in order to prevent undue wandering of the dye developer and development products from layer to layer. Other hydrophilic organic colloids yield less desirable results when used in the layers. For example, when some of the layers contain gelatin vehicle and interlayers of polyvinyl alcohol or cellulose acetate hydrogen phthalate are used, the layers tend to strip apart particularly when dry. Also, when gelatin is used throughout more uniform transfer of the alkaline processing solution and hydroquinone derivative through the layers is obtained and the dye developers comprising the final print transfer more readily to the reception layer.

The processing solution used to initiate development of the exposed sensitive elements containing the dye developers and hydroquinone derivatives, and which may contain the quaternary ammonium salt, should be strongly alkaline to accelerate the development activity of the dye developer as much as possible. Alkali metal hydroxides such as sodium hydroxide or alkaline salts such as sodium carbonate are advantageously used in the activator composition for this purpose. However quanternary ammonium hydroxides or volatile amines such as diethyl amine, which have the advantage of being volatilized from the prints and therefore leave no residue of alkali thereon which might tend to decom ose the dye images, may also be used. As mentioned previously, since the hydroquinone derivatives tend to be unstable in the strongly alkaline activator, they are preferably not incorporated in the processing solution although when the pyridinium salts are present, results are obtained which are satisfactory in other respects. The results most desired are obtained when the hydroquinone derivative is present in the layers of the sensitive elements. Therefore, no silver halide developing agent need be present in the processing solution.

The sensitive elements of the invention are of course adapted to use in a camera for taking pictures in the usual manner. Moreover, the development of the sensitive elements, i.e. the treatment with an alkaline activator solution to initiate development, can also be carried out in the camera by use of rupturable containers of processing solution used as illustrated in FIG. 1 of the drawings or other means may be used to spread the processing solution uniformly across the picture area of one or more consecutively exposed images and in contact with the reception layer. For this purpose, it may be desirable to use a processing solution containing in addition to strong alkali a thickening agent such as carboxymethyl cellulose or high-viscosity hydroxyethyl cellulose in suitable quantity to obtain the desired viscosity. Other means can be used such as spraying, dipping, roller coating, etc. to apply the processing solution to the exposed element and to initiate its development.

Thus, several consecutive exposures on a strip of the sensitive element can all be wetted with the alkaline processing solution and the dye developer images transferred to a single strip of reception material to provide several color prints in a single transfer operation. The alkaline processing solution may be replaced with water or a water solution of pH? .5 or less if the contiguous receiving sheet contains an alkali or an alkali releasing material. If the water or water solutions are integumented and incorporated in the light sensitive element or in the mordanted receiving sheet they may be released by suitable means such as by pressure or by heat.

One method for obtaining the color prints from a strip of the sensitive element containing a series of, for example, three or four consecutive exposures, is to apply a viscous processing solution from a releasably confining or rupturable container in a compartment such as a magazine, integral with a camera in the manner described below, to cause each of the exposed areas to be wetted with the processing composition at approximately the same time in contact with a strip of reception material and the corresponding multicolor images to transfer thereto to provide a series of colored images on a single strip of the reception material.

A different means for providing prints from the sensitive element containing a series of image exposures such as three or four consecutive exposures, is to expose the element to several subjects in a conventional camera not necessarily adapted to use of rupturable containers of the processing composition, and withdrawing the exposed element from the camera in a convenient manner so as to prevent fogging of the emulsions. Thus, the element can be exposed and wound upon itself on a spool in an ordinary roll-film type of camera so as to exclude light, by use of a light-impervious covering such as black paper, a cassette or a magazine. The element can then be withdrawn from the camera and placed in a convenient portable light-impervious enclosure of small dimension such as shown in FIG. 3, for application of the processing fluid to the element from, for example, a single rupturable container or several rupturable containers corresponding to the number of exposures recorded on the strip of sensitive element, or by application of the viscous or non-viscous fluid to the element by means of a wick, roller or similar applicator, so that each of the exposed areas is wetted. As a result the element comprising several image exposures on a single strip of differentially light-sensitive emulsion layers and subtractively colored dye developers contiguous to the silver halide of each emulsion layer, is wetted with the alkaline fluid in the presence of the onium salts, and preferably also in the presence of the hydroquinone derivatives, and brought into contact with the reception layer for a time suificient for adequate development of each image, to cause the silver halide in the several exposed areas of each emulsion layer to develop and thereby render the corresponding dye developers immobile and the dye developers in the unexposed portions of each of the several exposed areas to transfer to the reception layer and provide a series of prints thereon composed of the dye developers. in FIG. 3 is shown a schematic representation of an apparatus useful for this purpose and the process for making the series of prints from a sensitive element containing a series of exposures. The film 40 wound emulsion side inwards, having the structure shown in FIG. 1, Stage 1, and comprising a support having superposed thereon differently sensitized emulsions and contiguous dye developers, which has been exposed so as to record a series of multicolor subjects, is quickly passed between rollers 41 and 42 so as to pick up the alkaline activator solution 43, such as Activator II, contained in pan 44, which is supplied by roller 42 dipping into the solution. Thence the film continues between rollers 45 and 46 where it is brought into contact with the mordanted receiving sheet 47, such as Receiving Sheet A, to form the sandwich 48. The exposed silver halide in each emulsion layer then develops, corresponding dye developers become immobilized and the unreacted dye developers then transfer to sheet 47, after which the sandwich passes out of the enclosure and is stripped apart to provide a series of positive dye developer images on sheet 47 at 50.

Camera apparatus of the type useful for exposing and processing the sensitive elements of the invention have been described, for example, in U.S. Patent 2,435,717. Such cameras permit successive exposure of individual frames of the photosensitive element from the emulsion side as well as processing of an exposed frame by bringing the exposed portion of the photosensitive element in superposed relation with a portion of the print receiving element while drawing these portions of the film assembly between a pair of pressure rollers which rupture the container associated therewith and spread the processing liquid between and in contact with the photosensitive element and the corresponding registered area of the print receiving element. The photosensitive element and print receiving element during the spreading of the container contents become formed into a combination wherein the photosensitive element and print receiving element are so superposed with respect to each other that the spread liquid has access to both of the elements. This superposed relationship between the photosensitive and print receiving elements is maintained until the elements are stripped apart following the deposit on the print receiving element of the dye forming the final color image.

The reception layers to which the dye developers are transferred imagewise to obtain the multicolor images may be composed of various materials such as linear polyamides, proteins such as gelatin, polyvinyl pyrrolidones, poly-4-vinyl pyridine, polyvinyl acetate, polyvinyl alcohol, cellulose acetate, polyvinyl salicylal, partially hydrolyzed polyvinyl acetate, methyl cellulose, regenerated cellulose, carboxymethyl cellulose and hydroxethyl cellulose. These reception layers are coated on a suitable support such as a paper support, a transparent film or white pigmented cellulose ester support.

As will be apparent from a consideration of other color processes using dyes, the prints composed of the dye developers undergo decomposition to some extent when exposed to heat, light and moisture. Accordingly, it is advantageous to treat the prints to reduce these eifects as much as possible. For this purpose solutions of a number of materials can be swabbed on, sprayed on or otherwise applied to the prints to improve the stability of the dye images such as solutions of tannic acid, a condensation product of naphthalene sulfonic acid and formaldehyde, and polyvinyl pyrrolidinone. An exceptionally useful synergistic composition is a solution of polyvinyl alcohol containing a saccharide such as mannitol, levulose, arabinose, maltose, mannose, etc., neither the polyvinyl alcohol nor the saccharide being effective per se to stabilize the dye developer images.

In the processes of the invention it may be desirable to employ an antifoggant in the sensitive element, in the alkaline processing solution or in the reception element or in each, and a development arresting compound in the reception element. When development arresting compounds are present in the reception element rather than in the sensitive element or solution they do not become effective until dissolved by the processing solution and have migrated to the sensitive element under development. As a result, the latent image is allowed to develop very rapidly and the arrestment is delayed until the development of the exposed areas has essentially reached cornpletion before development is appreciably arrested. This results in the prevention of development in the unexposed areas and increases the amount of dye developer transferring. Additional improvement is obtained when the development arrestor is present in the reception layer and the mentioned quaternary salts are present in either the processing solution or the reception layer, or both. Suitable development arrestors are heterocyclic mercaptans such as mercaptotetrazoles and mercapto benzothiazoles, e.g. 1-phenyl-5-mercaptotetrazole, Z-mercaptobenzothiazole, etc. Many compounds usually considered to be anti-foggants for silver halide do not arrest development as desired.

In a further variation of the invention a small amount of a silver halide solvent such as alkali metal or ammonium thiosulfate or thiocyanate may be incorporated into the alkaline processing composition or the receiving layer, or both, with the result that the effective photographic speed of the process is increased. However, the efiect of the silver halide solvent becomes most apparent when either or both the mentioned hydroquinones and quaternary salts are present. Ordinarily the amount of silver halide solvent used is not sufficient to cause any appreciable amount of silver halide to be dissolved from the unexposed and undeveloped areas of the sensitive element and to be transferred to the reception layer.

The invention contemplates sensitive elements wherein the emulsion layers, contiguous hydroquinone derivatives and dye developer layers are integral with the support e.g. coated on a support capable of receiving the dye developer images, the support being of a nature such that it can be stripped away from the sensitive layers or a stripping layer may be provided between the reception layer and the other layers to facilitate the stripping operation. The alkaline fluid can thus be supplied as described above or in case the alkali is contained in one of the layers the fluid may merely be water supplied to release the alkali.

The silver halide emulsions of the sensitive elements of the invention include well-known silver halides and mixtures thereof, for example, silver bromide, silver bromoiodide or silver chlorobromide emulsions.

The following examples Will serve to illustrate the invention.

EXAMPLE 1.-HYDROQUINONE DERIVATIVES IN OUTER LAYER A sensitive element having the structure shown in Stage 1 of FIG. 1 was prepared by coating a subbed film support 10 with suitably hardened gelatin layers as follows:

Layer 11 An aqueous gelatin solution containing the cyan dye developer (Compound I above) dissolved in a mixture of N-n-butylacetanilide, 4-methyl cyclohexanone and dispersing agent Alkanol B, and the mixture passed through a colloid mill several times, coated and dried so as to volatilize the 4-methyl cyclohexanone.

Layers 14, 15 and 16 Gelatino silver bromoiodide emulsion layers sensitized, respectively, to the red, green and blue regions of the spectrum.

Layers 17 and 18 Gelatin interlayers.

Layer 12 An aqueous gelatin solution containing the magenta dye developer (Compound 11 above) dissolved in a mixture of cyclohexanone, N-n-butylacetanilide and Alkanol B, and the mixture passed through a colloid mill several times, coated and dried to volatilize the cyclohexanone.

Layer 13 4-methylphenylhydroquinone g 136 Methyl alcohol ml 136 Di-n-butyl phthalate ml 272 Heat at C. to dissolve, then cool to 40 C.

Part B:

10% gelatin solution g 1360 Water ml 1360 Alkanol B (5% aqueous solution) ml Heat to 40 C.

Part A was slowly added to Part B with the aid of mechanical agitation. The solution obtained was then passed through a Manton-Gaulin laboratory colloid mill five times. The colloid mill was then rinsed and the dispersion was adjusted to a weight of 3775 g., chill set and stored in a refrigerator.

The coating composition for layer 19 was prepared as follows.

Part I:

Dispersion D1 g 3775 Water m1 2225 Heat to 40 C.

Part II:

10% gelatin solution g 3180 Water ml 12,000 Mucochloric acid (2.7% aqueous solution) ml 515 Heat to 40 C., adjust pH to 5.5.

Parts I and II were then combined and diluted with water to 22,700 ml. This solution was coated as layer 19 of FIG. 1 to yield a coverage of approximately 120 mg. of gelatin per sq. ft. and 40 mg. per sq. ft. of 4'-methylphenylhydroquinone identified hereinafter as HQ.

Samples of the resultant element (No. 71) having the structure shown in FIG. 1, Stage 1, and samples of an identical element (No. 68) but which contained no 4'- methylphenylhydroquinone in layer 19, were then exposed to the same subject and wetted with Activators I, IIQ and IIIQ (below) in contact with Receiving Sheet A (below) composed of the support 20 and reception layer 21 (Tests 1 to 6). As a result the silver halide in exposed areas 23, 24 and 25 of each sample developed and the dye developers in the contiguous areas of layers 11, 12 and 13 thereunder became immobilized as a function of the development and the unreacted dye developers diifused imagewise and in register to the receiving sheet to yield a colored positive image composed of images 26, 27 and 28 as shown in Stage 2 of the drawings. In this process, due to the presence of the picolinium salts and partly due to the 4-methylphenylhydroquinone in the film, the dye developers in each of layers 11, 12 and 13 became immobilized at the required rate, extent and in the proper layers so that the resultant color prints have cleaner high lights (lower minimum density), the color separation is improved and color drop off is reduced compared to the control film No. 68 free of HQ.

The data of Tests 1 to 6 of the table below show the improvement in minimum density of the neutral scale of the prints resulting from the use of the quaternary salts. These tests show that when the element containing no HQ was processed with Activators IIQ and IIIQ (Tests 2 and 3) the minimum densities of the neutral scale of Tests 2 and 3 read by red and green light is reduced, compared to Test 1 where Activator 1 contained no quaternary salt. In addition visual examination of the samples of Tests 2 and 3 showed color contamination was decreased and drop off was considerably improved. It will be noted from Tests 4 to 6 that While HQ per se decreases minimum density (Test 4) when the quaternary is present (Tests 5 and 6) an additional decrease in minimum density is obtained.

EXAMPLE 2.HYDROQUINONE DERIVATIVE IN EMULSION LAYER A film No. 69 was prepared identical in structure to that of Example 1 except that sufiicient of the Dispersion D-1 was added to emulsion layer 16 (rather than to layer 19) to obtain 45 mg. of 4-methylphenylhydroquinone HQ per sq. ft. This element was processed as in Example 1 using Activators I, IIQ and IIIQ with the result shown by the data of the table (Tests 7, 8, and 9), where it can be seen that results similar to those of Example 1 were obtained. Also improvements in color contamination and drop off were obtained. It should be noted that the combination of the hydroquinone derivatives in the element and the quaternary salt in the process (Tests 1-9) gave improvements in color quality considerably superior to the use of either one alone.

EXAMPLE 3.SILVER HALIDE SOLVENT AND PYRIDINUM SALT IN ACTIVATOR Films were prepared as described in Example 1 except that a film No. contained no HQ, No. 18 contained 40 mg. HQ per sq. ft. in layer 19, film No. 14 had 40 mg. HQ per sq. ft. in layer 18 and film No. 75 had 40 mg. HQ per sq. ft. in layer 17. The films were processed in Activators IVQ and V below each containing the silver halide solvent sodium thiosulfate and IVQ also contained the pyridinium salt. As shown in part by the data of Tests 10 to 17 of the table, improved color values, decreased minimum densities, drop off and color contamination were obtained regardless of the position 20 of the HQ in the film, and particularly Where the pyridinium salt was present in the activator solutions.

EXAMPLE 4.PYRIDINUM SALT IN THE RECEIVER Film No. 68 prepared as in Example 1 (no HQ in layer 19), film No. 69 of Example 2 (HQ in layer 16) and film No. 71 (HQ in layer 19) were each exposed, wetted with Activator I in contact with Receiver B (below) containing the pyridinium salt to transfer multicolor images to the receiver. As a result the color values of the prints were much improved compared to similar prints made upon Receiver A free of the pyridinium salt. The density data of Tests 18, 19, and 20 show in part that the HQ in layers 16 and 19 and the pyridinium salt in Receiver B, substantial reduction in the minimum densities is effected, as Well as improvement in color contamination and drop off.

Activator I.An aqueous solution containing 3.5% of high viscosity hydroxyethyl cellulose, 4.5% of NaOH, 2% benzotriazole.

Activator llQ.Activator I plus 2.0% of l-phenethyl- 2-picolinium bromide.

Activator IIIQ.Activator I plus 2.0% l-benzyl-2- picolinium bromide.

Activator lVQ.-Activator IIIQ plus 1.0% sodium thiosulfate.

Activator V.Activator I plus 1% sodium thiosulfate.

Activator VI.4% aqueous carboxymethyl cellulose, 4% NaOI-I, 1% sodium thiosulfate, 0.2% S-nitrobenzimidazole, 5% hexamethylenetetramine.

Activator VII.Activator VI plus 2% 1-benzyl-2-picolinium bromide.

Activator VIIL-Activator VI plus 2% 1-phenethyl-2- picolinium bromide.

Activator IX .Activator VI plus 2.0% 1-phenethyl-3- picolinium bromide.

Activator X.Activator VI plus 2.0% pyridinium bromide.

Activator XIQ.-Activator I plus 2% 1-phenethyl-2- picolinium bromide.

Activator XIIQ.Activator I plus 2% l-ethyl pyridinium bromide.

Activator XIIIQ.-Activator I plus 2% l-phenethyl pyridinium bromide.

Activator XIVQ.-Activator I plus 5% tetramethylammonium bromide.

Activator XVQ.Activator I plus 2% 1-phenethyl-3- picolinium bromide.

l-phenethyl Receiving Sheet A A white pigmented cellulose ester support carrying a gelatin layer containing a mixture of poly-4-vinyl pyridine mordant and 1-phenyl-5-mercaptotetrazole.

Receiving Sheet B A white pigmented cellulose ester support carrying a gelatin layer containing a mixture of poly-4-vinylpyridine, 1- phenyl 5 mercaptotetrazole and l-phenethyl-Z-picolinium bromide.

In a similar manner the other elfective hydroqinones may be used in the films containing the dye developers and the other effective quaternary salts preferably in the alkaline processing solution or the reception layer or both.

EXAMPLE 5 In the manner of Example 1 except using Activator IVQ, a series of 5, 10, 20, 40 and mg. of HQ per sq. ft. were incorporated into layer 19 from which it was observed that the mentioned improvements were obtained at the 5 and 10 mg. levels: however, optimum results were obtained in the range of 20 to 100 mg.

Similar results were obtained when the concentration series was used in layer 16.

-2.1 EXAMPLE 6 In the manner of Example 1 except using Activator IVQ, the following hydroquinones were used in layer 19:

Compound No. MgJft.

4-eh1orophenyl hydroquinone 44 phenyl hydroquinone 28 phenoxy hydroquinone" 40 2,5-dioetyl hydroquinone 50 EXAMPLE 7 Samples of the sensitive element prepared as described in Example 1 and containing the hydroquinone derivative in the outermost layer, were processed as in Example 1 and using Receiving Sheet A, but using Activators VI, VII, VIII, IX and X above with the result that sensitometric scales of the prints processed with the Activators VII to X containing the quaternary salts, all exhibited lower minimum densities than the prints processed with Activator VI free of the quaternary salt. However, the sensitometric scales of the prints processed with Activators IX and X showed a high level of color drop-E since the quaternary salts used were structurally incapable of forming methylene bases, whereas the scales of the prints obtained with Activators VII and VIII, containing the quaternary compounds forming methylene bases, showed extremely low color drop-01f and very low color contamination.

EXAMPLE 8 Samples of the sensitive element of Example 1 were processed as in Example 1 with Activators I, XIQ to XVQ with the result that all of the Activators XIQ to XVQ all gave prints showing reduced minimum density, but Activator XIQ also greatly reduced drop-off and the colors were much more saturated.

Neutral Scale Ex- Test ample No.

Aeti- Re- Film No. ceiver D. Min.

Green Blue 1 68(Control) I do ,do

4 71 (HQin19) I ,do II d0 7 69(HQin16) I do 1O 15 (Control)l do 12 18(IgQin19) V o 14 14(IgQin18)--. V o

16 75 (HQin17)--. V

18 68 (Control) (eonta)ins its .31 .41 .89

71 (HQin 19)... I

The unique results obtained with the heterocyclic quaternary ammonium compounds forming methylene bases appears to be due to their reaction with two moles of a quinone (obtained by oxidation of a dye developer or other hydroquinone derivative) to form an addition product of the quinone and the methylene base and re- 'ene glycol 22 generate a hydroquinone, as shown by James, Snell and Weissberger J.A.C.S. 60-, 2084 (1938).

The emulsion addenda described in the Whitmore et al. US. patent application Serial No. 734,141, filed May 8, 1958, and French Patent 1,205,755, August 17, 1959, including the noble metal salts, stannous salts, polyamines, optical sensitizing dyes, mercury and azaindene stabilizing compounds, quaternary ammonium salt and polyethylspeed-increasing compounds, plasticizers, hardeners, coating aids in colloid vehicles disclosed therein may be used advantageously in the silver halide emul sion layers and adjacent layers of the sensitive elements of the present invention.

What we claim is:

1. In the processing of an exposed photographic element comprising a support, a plurality of light-sensitive silver halide emulsion layers sensitive to light of diflferent regions of the spectrum, and a dye developer which is both a silver halide developing agent and a dye contiguous to the silver halide of each of said silver halide emulsion layers, said processing being efiected by treating said photographic element with an alkaline liquid, developing latent images in the regions of exposure of said silver halide emulsion layers and thereby immobilizing dye developers in said regions of exposure, dye developers in undeveloped regions diffusing imagewise in register to a dye developer reception layer, the improvement which comprises effecting said processing in the presence of a heterocyclic quaternary ammonium compound capable of forming a diffusible methylene base in said alkaline liquid.

2. A process as defined by claim 1 wherein the heterocyclic quaternary ammonium compound has the formula wherein:

(a) n is an integer of 0 to 1,

(b) D represents the nonmetallic atoms necessary to complete a heterocyclic nucleus,

(0) X is an anion,

(d) R is selected from the group consisting of an alkyl radical, an aryl radical and an aralkyl radical, and (e) R is selected from the group consisting of a hydrogen atom, an alkyl radical, an aryl radical and an aralkyl radical.

3. A process as defined by claim 2 wherein the D substituent represents the nonmetallic atoms necessary to complete a pyridinium nucleus.

4. In the processing of an exposed photographic element comprising a support, superposed red, green and blue light-sensitive silver halide emulsion layers, and a dye developer which is both a silver halide developing agent and a dye contiguous to the silver halide of each of said silver halide emulsion layers, said processing being effected by treating said photographic element with an alkaline liquid, developing latent images in the regions of exposure of said silver halide emulsion layers and thereby immobilizing dye developers in said regions of exposure, dye developers in undeveloped regions diffusing imagewise to the surface of said photographic element, and transferring the resulting ditfused images from said undeveloped regions in register to a dye developer receiving sheet superposed on said photographic element, the improvement which comprises using in said alkaline liquid a heterocyclic quaternary ammonium compound capable of forming a diiiusible methylene base in said alkaline liquid and having the formula 23 wherein:

(a) n is an integer of to 1, (b) D represents the nonmetallic atoms necessary to complete a pyridinium nucleus, (c) X is an acid anion, (d) R is an aralkyl radical, and (e) R is a lower alkyl radical.

5. In the processing of an exposed photographic element comprising a support, superposed red, green and blue light-sensitive silver halide emulsion layers, and a dye developer which is both a silver halide developing agent and a dye contiguous to the silver halide of each of said silver halide emulsion layers, said processing being eifected by treating said photographic element with an alkaline liquid, developing latent images in the regions of exposure of said silver halide emulsion layers and thereby immobilizing dye developers in said regions of exposure, dye developers in undeveloped regions diffusing imagewise to the surface of said photographic element, and transferring the resulting diffused images from said undeveloped regions in register to a dye developer receiving sheet superposed on said photographic element, the improvement which comprises using in said alkaline liquid at heterocyclic quaternary ammonium compound capable of forming a difiusible methylene base in said alkaline liquid and having the formula wherein:

(a) n is an integer of 0 to 1,

(b) D represents the nonmetallic atoms necessary to complete a pyridinium nucleus,

(c) X is an acid anion, and

(d) R and R are each lower alkyl radicals.

6. In the processing of an exposed photographic element comprising a support, superposed red, green and blue light-sensitive silver halide emulsion layers, and a dye developer which is both a silver halide developing agent and a dye contiguous to the silver halide of each of said silver halide emulsion layers, said processing being effected by treating said photographic element with an aqueous alkaline solution, developing latent images in the regions of exposure of said silver halide emulsion layers and thereby immobilizing dye developers in said regions of exposure, dye developers in undeveloped regions diffusing imagewise to the surface of said photographic element, and transferring the resulting diffused images from said undeveloped regions in register to a dye developer receiving sheet superposed on said photographic element, the improvement which comprises using in said alkaline solution a heterocyclic quaternary ammonium compound capable of forming a dilfusible methylene base in said alkaline solution selected from the group consisting of 7. A process as defined by claim 6 wherein the silver halide emulsions are gelatino-silver bromoiodide emul- SlOI'lS.

References Cited in the file of this patent UNITED STATES PATENTS 2,334,864 Carroll ct al Nov. 23, 1943 2,784,090 Carroll Mar. 5, 1957 2,868,077 Ryan Jan. 13, 1959 2,886,437 Piper May 12, 1959 2,983,606 Rogers May 9, 1961 3,017,270 Tregillus Jan. 13, 1962 3,034,894 Jefireys May 15, 1962 3,039,869 Rogers et a1 June 19, 1962 3,061,453 Rogers Oct. 30, 1962 3,077,400 Rogers et al. Feb. 12, 1963 FOREIGN PATENTS 221,880 Australia May 27, 1959 OTHER REFERENCES James et al.: JACS, 60, 20842093 (1938). Sci. Lib.)

Glafkides: Photographic Chemistry, Fountain Press, London (1958), pp. -57 and 156-157. (Copy in Sci.

Lib.)

Mosher: American Dyestuif Reporter, January 20, 1941, pp. 1 32-1 38. (Copy in Sci. Lib.)

( py in 

1. IN THE PROCESSING OF AN EXPOSED PHOTOGRAPHIC ELEMENT COMPRISING A SUPPORT, A PLURALITY OF LIGHT-SENSITIVE SILVER HALIDE EMULSION LAYERS SENSITIVE TO LIGHT OF DIFFERENT REGIONS OF THE SPECTRUM, AND A DYE DEVELOPER WHICH IS BOTH A SILVER HALIDE DEVELOPING AGENT AND A DYE CONTIGUOUS TO THE SILVER HALIDE OF EACH OF SAID SILVER HALIDE EMULSION LAYERS, SAID PROCESSING BEING EFFECTED BY TREATING SAID PHOTOGRAPHIC ELEMENT WITH AN ALKALINE LIQUID, DEVELOPING LATENT IMAGES IN THE REGIONS OF EXPOSURE OF SAID SILVER HALIDE EMULSION LAYERS AND THERBY IMMOBILIZING DYE DEVELOPERS IN SAID REGIONS OF EXPOSURE, DYE DEVELOPERS IN UNDEVELOPED REGIONS DIFFUSING IMAGEWISE IN REGISTER TO A DYE DEVELOPER RECEPTION LAYER, THE IMPROVEMENT WHICH COMPRISES EFFECTING SAID PROCESSING IN THE PRESENCE OF A HETEROCYCLIC QUATERNARY AMMONIUM COMPOUND CAPABLE OF FORMING A DIFFUSIBLE METHYLENE BASE IN SAID ALKALINE LIQUID. 